This invention is related to alkoxysilane terminated moisture-hardening polyurethanes, to a method for reducing their viscosity without solvents or plasticizers, and to the use of said reduced-viscosity mixtures in adhesive and sealing compounds.
The use of silylated polyurethanes in construction adhesive and joint sealant compounds provides faster cure times, greater durability and improved adhesion, elongation, tensile strength, and elasticity in comparison with the compounds that they replace. It is not uncommon, however, to encounter viscosities of a million centipoises when formulating such compounds with silylated polyurethanes. A desirable viscosity is on the order of about 20,000 centipoises. Solvents and plasticizers have thus become a necessary part of the formulator's art when processing and application problems are caused by such high viscosities.